docs: def prototype_adjacency(self, n_block_features, alpha=None):
          """Build a new graph.
  
          Doc for ".create(n_features, alpha)"
  
          Parameters
          -----------
          n_features : int
  
          [alpha] : float (0,1)
              Unused.
  
          Each graph will have a minimum of
  
              (n_blocks * n_block_features**2 - n_blocks) / 2
  
          edges and exactly this amount if chain_blocks=False.
  
          Returns
          -----------
          (n_features, n_features) matrices: covariance, precision, adjacency
          """
          return -np.ones((n_block_features, n_block_features)) * 0.5 + self.prng.uniform(
              low=self.low, high=self.high, size=(n_block_features, n_block_features)
          )